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Studies to the Functioning of Automotive Exhaust Catalysts Using In-Situ Positron Emission Tomography
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Abstract
Studying the reactions in an automotive exhaust catalyst is complex as the exhaust gases contain many components of which the composition constantly varies and the catalyst contains different active components. To elucidate reaction kinetics in exhaust catalysis, the application of a technique stemming from nuclear medicine, i.e. Positron Emission Tomography, has been developed.
Short lived positron emitting nuclides 11C (t1/2 = 20 min), 13N (t1/2 = 10 min) and 15O (t1/2 = 2 min) have been used to synthesise actual reactant molecules such as 11CO, 11CO2, 11CH4, 13N2, 15OO, C15O and C15OO. Pulses of picomole amounts of these labelled reactants have been added to synthetic exhaust gases, which were led over commercial and model automotive catalysts in a small plug flow reactor. The labelled compounds were detected and identified in both reactant and product stream using a gas chromatograph equipped with a proportional counter. On top of that, the labelled reactants in the catalyst bed could be monitored right through the reactor wall using a Positron Emission Tomograph, with a resolution of 1 cm in place and 1 s in time. Hereby, a large amount of information on the residence time of the reactants is obtained directly from the catalyst surface under actual reaction conditions.
By means of these experiments the rate limiting step in the carbon monoxide oxidation on platinum and rhodium under cold start conditions of a car were found to be the availability of free noble metal surface for the dissociative oxygen adsorption. The different behaviour of rhodium and platinum in the CO oxidation in the presence of NO was found to be the higher tendency for NO dissociation of rhodium. A strong interaction was found between gas phase CO2 and CeO2 at the catalyst surface, whereby the oxygen atoms contained in lattice CeO2 exchange rapidly with the oxygen atoms of the adsorbed CO2. A mathematical model for the reaction kinetics was constructed and by simulating the experiments with this model the kinetic parameters were quantified.
The experiments demonstrate the utility of short-lived positron emitter nuclides such as 11C, 13N and 15O, for non-invasive and in-situ catalyst research. The importance of using in-situ catalyst surface information in understanding the working of automotive exhaust catalysts under actual reaction conditions is emphasised.
Authors
Citation
Vonkeman, K., Jonkers, G., and van Santen, R., "Studies to the Functioning of Automotive Exhaust Catalysts Using In-Situ Positron Emission Tomography," SAE Technical Paper 910843, 1991, https://doi.org/10.4271/910843.Also In
References
- Williamson, W.B. Perry, J. Gandi, H.S. Bomback, J.L. Appl. Catal. 15 277 1985
- Taylor, K.C. Catalysis, Science and Technology Anderson, J.R. Boudart, M. 5 2 119 1984
- Walsh, M.P. Platinum Met. Rev. 30 3 106 1986
- Prairie, M.R. Cho, B.K. Oh, S.H. Shinouskis, E.J. Bailey, J.E. Ind. Eng. Chem. Res. 27 1396 1988
- Dictor, R. J. Catal. 106 458 1987
- Su, E.C. Rothschild, W.G. J. Catal. 99 506 1986
- Schuth, F. Wicke, E. Bunsenges Ber. Phys. Chem. 93 191 1989
- Klein, R.L. Schwartz, S. Schmidt, L.D. J. Phys. Chem. 89 4908 1985
- Fisher, G.B. Oh, S.H. Carpenter, J.E. DiMaggio, C.L. Schmieg, S.J. Goodman, D.W. Root, T.W. Schwartz, S.B. Schmidt, L.D. “Catalysis and Automotive Pollution Control” Crucq A. Frennet A. 215 Elseviers Science Publishers B.V. Amsterdam 1987
- Peden, C.H.F. Goodman, D.W. Blair, D.S. Berlowitz, P.J. Fisher, G.B. Oh, S.H. J. Phys. Chem. 92 1563 1988
- Hahn, T. Lintz, H.-G. Surf. Sci. 211/212 1030 1989
- Daniel, D.W. J. Phys. Chem. 92 3891 1988
- Hecker, W.C. Bell, A.T. J. Catal. 84 200 1983
- Dictor, R. J. Catal. 109 89 1988
- Taylor, K.C. Schlatter, J.C. J. Catal. 63 53 1980
- Bennett, C.O. Laporta, L.M. Cutlip, M.B. “Catalysis and Automotive Pollution Control” Crucq A. Frennet A. 143 Elseviers Science Publishers B.V. Amsterdam 1987
- Carberry, J.J. Acc. Chem. Res. 18 358 1985
- Jin, T. Okuhara, T. Mains, G.J. White, J.M. J. Phys. Chem. 91 3310 1987
- Koberstein, E. Wannemacher, G. “Catalysis and Automotive Pollution Control” Crucq A. Frennet A. 155 Elseviers Science Publishers B.V. Amsterdam 1987
- Phelps, M.E. Mazziotta, J.C. Schelbert, H.R. Positron Emission computed Tomography and Autoradiography Raven Press 1986 New York
- Webb, S. Medical Science Series The Physics of Medical Imaging Hilger Adam Bristol 1988
- Phelps, M.E. Hoffman, E.J. Huang, S.C. Kuhl, D.E. J. Nucl. Med. 19 6 635 1978
- Hilger, A. The Physics of Medical Imaging Webb S. Bristol, U.K. 1988
- Knoll, G.T. Radiation Detection and Measurement 2nd John Wiley & Sons New York 1989
- Vonkeman, K.A. Jonkers, G. Van der Wal, S.W.A. Oosterbeek, H. de Jong, J. Van Santen, R.A. J. Catal.
- Strijckmans, K. Annual Report 1987 Ed. Dams, R. 99 1988
- Van den Bergen, E.A. Jonkers, G. Strijckmans, K. Goethals, P. Nucl. Geophys. 3 4 407 1989
- Williams, C.W. Crabtree, M.C. Burke, M.R. Keyser, R.M. Burgiss, S.G. Hoffman, E.J. Phelps, M.E. IEEE Trans. on Nucl. Sci. NS-28 1736 1981
- Hoffman, E.J. Phelps, M.E. Huang, S.C. J. Nucl. Med. 24 245 1983
- Vonkeman, K.A. Jonkers, G. Van der Wal, S.W.A. Oosterbeek, H. De Jong, J. Van Santen, R.A. J. Catal.
- Vonkeman, K.A. Van der Wal, S.W.A. Jonkers, G. Van Santen, R.A. Chem. Eng. Sci.
- Yates, J.T. Jr. Thiel, P.A. Merrill, R.P. J. Catal. 65 461 1980
- Oh, S.H. Fisher, G.B. Carpenter, J.E. Goodman, D.W. J. Catal. 100 360 1986
- Vonkeman, K.A. Van der Wal, S.W.A. Jonkers, G. Van Santen, R.A. Chem. Eng. Sci.
- Graham, W.R.C. Lynch, D.T. AIChE J. 33 5 792 1987
- Lynch, D.T. Emig, G. Wanke, S.E. J. Catal. 97 456
- Jin, T. Okuhara, T. Mains, G.J. White, J.M. J. Phys. Chem. 91 3310 1987
- Daniel, D.W. J. Phys. Chem. 92 3891 1988
- Li, C. Sakata, Y. Arai, T. Domen, K. Maruya, K. Onishi, T. J. Chem. Soc. Faraday Trans. 1 85 4 929 1989
- Li, C. Sakata, Y. Arai, T. Domen, K. Maruya, K. Onishi, T. J. Chem. Soc. Faraday Trans. 1 85 6 1451 1989
- Barrault, J. Alouche, A. Appl. Catal. 58 255 1990
- Schwartz, S.B. Fisher, G.B. Schmidt, L.D. J. Phys. Chem. 92 389 1988
- Campbell, C.T. White, J.M. Appl. Surf. Sci. 1 347 1978